Project Summary (current research and goals) My research aims to improve the mobility of veterans with lower limb amputation, reduce their risk of injury, and enhance their comfort while wearing a prosthesis. I explore innovative ideas that could dramatically advance the state-of-the-art and use randomized clinical trials to determine the efficacy and efficiency of currently- prescribed interventions to guide clinical decision-making. The exploration of innovative ideas offers the opportunity to dramatically alter functional outcomes through the development of highly imaginative, novel devices. With the help of veterans, graduate students, professional staff, and colleagues, I am currently developing six lower limb prostheses to address the mobility, injury, and comfort problems of veterans with lower limb amputation. To improve mobility, two of these prostheses explore balance improvement while walking on uneven terrain; both have inverting and everting ankles with controllable stiffness and one can conform to terrain undulations like the natural limb. As VA Merit Review support for this research recently ended, I plan a grant submission to extend this work in December 2018. A third mobility- enhancing prosthesis I am developing uses a biologically-inspired actuator and incorporates a learning algorithm that can adapt propulsive outputs to changing needs (the topic of a pending VA Merit Review). Carrying a heavy box or donning a backpack exemplify short duration, sudden onset changes to actuation and propulsive needs, while weight gains associated with pregnancy are an example of slow, but long-lasting changes. I am exploring how machine learning algorithms may enable intuitive prosthesis control in response to these changing conditions. To reduce soft tissue injury risk, the fourth and fifth prostheses I am developing aim to reduce the torsional loads applied the residual limb. One has variable torsional stiffness that can change with walking speed, turning direction, and user preference. The other, inspired by the function of the natural limb, couples sagittal and transverse plane motions and is the topic of a recently funded VA Merit Review. With intellectual property protections in place, this biomimetic prosthesis may offer a high payoff in the commercial market place. Finally, to enhance comfort, the sixth prosthesis I am developing aims to expel perspiration from the socket-suspension system during vigorous activities before discomfort and slippage occur. The work to develop this comfort- enhancing prosthesis was recently selected for DOD funding. Each of these novel devices tackles a clinically- driven problem for which there is currently no solution. A more immediate goal of my research is to provide clinicians with evidence to guide clinical decision-making. A challenging task faced by providers for individuals with lower limb amputation is choosing among the 200+ commercially available prosthetic feet. To help inform their decisions, I am making a graphical user interface tool available to aid with the prescription process. This tool uses experimental data from a robotic gait simulator that measures gait influencing characteristics of prosthetic feet. To explore the efficiency of different rehabilitation interventions, I am collecting activity level data from a geographically-dispersed population with a cloud-based system. With over ninety participants and nearly three years of observations, this rich data set will provide fundamental knowledge. On a subset of this population, I am using a custom-built instrument to classify and count the number of steps taken during different locomotion activities (i.e., walking straight on level ground, up and down stairs, up and down ramps, and turning left and right) to provide perspective on the design requirements of next generation prostheses. I believe the knowledge disseminated from my research will provide evidence to guide both commercial development of new products and current clinical practice. I expect both to lead to substantial quality of life improvements for veterans with lower limb amputation.